Marine mammal vocalizations and shipping patterns off the California coast near Sur Ridge

Abstract

Studying the effects of anthropogenic noise on marine life is the focus of many ongoing research efforts, and regional studies can provide useful insight into the broader issues. Waters off the central California coast are well known for the rich occurrence of a variety of marine mammal species. The region also contains important ship routes used by vessels transiting between major US west coast ports. Here, we examine the relationship between marine mammal vocalizations collected near Sur Ridge and local shipping patterns determined from automatic identification system (AIS) reports broadcast by ships passing through the region. Passive acoustic recordings of vocalizations were acquired with a moored high-frequency acoustic recording package (HARP) over the frequency bandwidth 10 Hz–100 kHz. Number of vessels within several different radii from the HARP mooring is correlated with presence/absence data of several baleen whale, beaked whale, and dolphin species over 5-min intervals between January 2009 and November 2010. We also examine whether diel patterns of marine mammal distribution are influenced by diel patterns in ship traffic. These data will be useful for establishing mammal-vessel interaction rates in the Monterey Bay National Marine Sanctuary. [Research supported by US Navy CNO(N45)].